The number of lesbians using IVF is increasing, new figures show.

Between 1999 and 2006, the number of treatment cycles for lesbian couples tripled from 300 per year to almost 1,000.

During the same time period, the number of treatment cycles undergone by single women only doubled.

But experts say that the biggest group of women leading the surge in vitro fertilisation are women of all sexualities aged 40-plus.

Almost 40,000 cycles of treatment were provided to these women in 2006, and their numbers increased by 15% in just one year.

Angela McNab, chief executive of the Human Fertilisation and Embryology Authority (HFEA), which published the figures on the occasion of the authority’s annual conference in London on Tuesday, told The Independent that the growth in demand from women over 40 was worrying.

She said: “Scandinavian countries are seeing the trend to delay motherhood even more markedly.

“It is a matter of concern. We may need to remind women about the biological clock and the difficulty of achieving pregnancy over 40.”

Currently, each NHS primary care trust separately allocates funds for IVF treatment. Any woman wanting to undergo IVF treatment will have to be assessed by a doctor who will do a child welfare assessment.

During that assessment, they will assess the child’s need for a father. They inspect the individual’s family structure and gay-friendly trusts will endorse the use of IVF where the child would have a strong male role model, such as an uncle or neighbour.

However, some NHS PCTs will veto the use of IVF in cases where they believe the child needs a father.

This legislation is currently under review by the Government.

The average cost of a cycle of treatment ranges from £4,000 to £8,000. A woman having three or four cycles, the average number needed before a woman conceives, faces a bill of at least £12,000 and up to £32,000.